Method of applying antihalation layers to polyester film



March 21, 1961 C. B. THOMPSON ETA].

METHOD OF APPLYING ANTIHALATION LAYERS TO POLYESTER FILM Filed March 6, 1959 Fig./

POLYESTER SHEET/N6 Polymer of the Following Constituents Acrylonitr/le or Methyl Acry/ate,

Vinyl/done Chloride, and optionally, Acrylic Acid or ltaconic Acid Fig. 2

Cyan Dyes POLYESTER SHE E TING Polymer Layer (See Above) Fig.3

of Polymer (See Above) Apply to Polyester Sheeting an Aqueous Emulsion Containing 2 4 to 50 2 I DRYl/VGI (Polymer Application) Sheeting) Apply on Aqueous Solution of Acry/ate Acrylic Copoh/mer, Ammonium Hydroxide, Yellow, Magenta and cyan Dyes withA Spreading Agent K The A cry/ate Acry/ic Acid and Dyes Plus Eliminating the Ammonia and Water) CRAY TON B. THOMPSON GEORGE H. PIERCE INVENTORS ATTORNE 5 United States Patent METHOD OF APPLYING ANTIHALATION LAYERS TO POLYESTER FILM Filed Mar. 6, 1959, Ser. No. 197,511

11 Claims. 01. 117-34 This invention relates to removable antihalation layers for photographic film. More particularly this invention concerns a method of applying a certain type of antihalation layer to polyester film base.

As is Well known in the photographic industry, it is usual practice to apply to film base or support various layers such as antihalation layers, antistatic layers and the like. With the older film supports of cellulose esters such as cellulose acetate and cellulose acetate butyrate film base material, such layers have been applied from organic solvents. These organic solvents have comprised acetone, methanol and other well-known commercially available solvents which readily attack such older film base. That is, in accordance with prior art procedures, the materials for the antihalation layer or the like were dissolved in organic solvents, this organic solution applied to the support and then the organic solvents were removed leaving the layer deposited on an bonded to the film support.

With the advent of film support exhibiting hydrophobic surfaces such as the commercially available polyester films specifically illustrated by polyethylene terephthalate film, conventional organic solvents and methods of the prior art are no longer satisfactory because of the inertness of the polyester. Although certain organic solvents have been suggested for dissolving polyesters, in many instances such solvents are rather expensive, corrosive or otherwise may present problems.

It is apparent, therefore, that the development of improved methods for applying antihalation and the like layers to polyester film or the like film surfaces presenting a hydrophobic and resistive area upon which the layers are to be deposited represents a highly desirable result. After extended investigation, we have found a simple and effective method of applying layers to such surfaces employing coating materials in a certain type of aqueous enviroment.

This invention has for one object to provide a method for applying various layers to film supports which exhibit inert or hydrophobic surfaces. A particular object is to provide a method for applying antihalation layers and the like to polyethylene terephthalate film products. .Still another object is to provide a method of the class indicated where the layer applied may be rendered substantially water insoluble but which is soluble in photographic developers. Still a further object is to provide a method which is relatively simple and economical. Other objects will appear hereinafter.

In the broader aspects of our' invention we have found that certain aqueous solutions of polymers, which polymers may have incorporated therein coloring materials or other materials for antihalation and antistatic effect, may be coated onto film supports having a hydrophobic or resistive surface. Such film support'is exemplified by polyester film which may have had applied to the film during the manufacture thereof a latex layer before the film is oriented and crystallized. We have found that the coatings of the present invention pro- Patented Mar. 21, 1961 vide a removable backing which can give halation protection to photographic film comprised of polyester base. We may use copolymers of methacrylic acid and methacrylate esters such as methyl, ethyl, propyl or butyl as alkali soluble carriers for fugitive dyes and/or colored pigments.

We have found that when the copolymer of methyl or butyl methacrylate-methacrylic acid, for example, is treated with small amounts of ammonia, a water soluble salt is formed. After proper curing, the ammonia is released leaving a moisture resistant acid copolymer clear film which is easily removed in alkaline solution such as photographic developers.

'Aqueous ammonia solutions of the various polymers referred to above may be coated to latex (methyl acrylate-vinylidene chloride-itaconic acid in a ratio of 15/83/02) coated biaxially oriented crystallized polyethylene terephthalate sheeting or other polyester sheeting. The polymer, dye and/or pigment mixture adheres to the sheeting surface to a useful. degree.

The coatings after drying exhibit excellent removability (alkali solubility) and .good moisture resistance.

For a more complete understanding of this invention reference is made to the attached drawing forming a part of the instant application.

Fig. 1 is a diagrammatic across section on an enlarged scale of one embodiment of a polyester sheet which has a latex or aqueous emulsion polymer thereon. Fig. 2 is a diagrammatic cross section on an enlarged scale showing an embodiment in accordance with the present invention wherein a polymeric coating is applied which contains certain dyes. Fig. 3 is a flow sheet illustrating one embodiment of the process for coating polymeric sheeting with an antistatic layer in accordance with the present invention. Inasmuch as these figures may be readily understood from the legends thereon, further description appears to be unnecessary.

The following examples will illustrate certain preferred embodiments of the present invention.

Example I A mixture of: Percent 5 Butyl methacrylate-methacrylic acid polymer 1.75 Ammonium hydroxide (28% NH 0.30 Yellow dye of this composition, 4-[3-ethy1-2(3)- benzoxazolylidene)ethylidene] 3 methyl-l-(psulfophenyl) -5-pyrazolone 0.30 Magenta dye of this composition, 4-[(3-ethyl- 2(3) benzoxazolylidene)butenylidene] 3 methyl 1 p sulfophenyl 5 py-razolone 92.65 H O, in accordance with the present invention component of our coating composition. The coating had good adhesion. The backing is readily dissolved in photographic developers to give a clear film. The dyes are decolorized in the developer.

' Example II A mixture in accordance with the present invention, of:

Percent 5 Butyl methacrylate-methacrylic acid polymer 1.75 Ammonium hydroxide (28% NH;)

was applied by roller coating to polyethylene terephthalate sheeting of the same kind as described in the preceding example. The coating was dried to give a backing with halation protection for panchromatic emulsions. The coating had good adhesion. The backing is readily dissolved in photographic developers to give a clear film. The dyes are decolorized in the developer.

Example III A mixture of:

Percent 4 Methyl methacrylate-methacrylic acid polymer ground with 30% by weight Peerless carbon black 1 Ammonium hydroxide (28% NH 0.05 Triton X-100 (a concentrated wetting agent sold by Rohm & Haas Co.) and comprised of p-tertiary octylphenoxypolyethoxyethanol was applied by roller coating to biaxially oriented crystal lized polyethylene terephthalate sheeting as above. The coating was dried to give a halation and antistatic protection for panchromatic emulsions. The coating had good adhesion and a resistivity of 050x10 ohms. The backing is readily dissolved in photographic developers to give a clear film.

Example IV A mixture of:

Percent 0.30 Carbon (Aquablak H, 30% carbon) 1.00 Butyl methacrylate-methacrylic acid 0.30 Ammonium hydroxide (28% NH 0.02 Triton X-lOO was applied by roller to biaxially oriented crystallized polyethylene terephthalate sheeting. The application was dried. Optical density was 0.25 and resistivity was 0.50 10 ohms. The coating had good adhesion. The coating readily dissolves in photographic developers.

Example V A mixture of:

Percent Butyl methacrylate-methacrylic acid polymer 1.75 Ammonium hydroxide (28% NH 0.30 Yellow dye of this compositon, 4-[(3-ethyl-2(3) benzoxazolylidene)ethylidene] 3 methyl 1- (p-sulfophenyl -5-pyrazolone 0.30 Magenta dye of this composition, 4-[(3-ethyl-2(3)- benzoxazclylidene) butenylidene] 3 methyl 1- p-sulfophenyl-5-pyrazolone was applied by roller coating to latex (methyl acrylatevinylidene chloride-itaconic acid in a ratio of 15/ 83/02) coated polycarbonate sheeting and was dried to give a backing with halation protection for orthochromatic emulsions. The coating had good adhesion to the hydrophobic surface of the polycarbonate sheeting and was removable in various developers, as was the situation in the preceding examples.

Although in the above examples we have described our coatings as applied to polyester sheeting or film which had a latex coating thereon, many variations of the latex may be used for coating the polyester sheet before it is oriented and crystallized. In addition to methyl acrylate-vinylidene chloride-itaconic acid, the following terpolymers have also been used in a ratio of 15/83/02:

Acrylonitrile-vinylidene chloride-acrylic acid Acrylonitrilevinylidene chloride-itaconic acid n-Butyl acrylate-vinylidene chloride-itaconic acid These dimeric polymers are also useful: Acrylonitrilevinylidene chloride and n-butyl acrylate-vinylidene chloride in a ratio of 15/85.

As described above, our invention functions very satisfactorily for applying an antihalation layer over conventional latex treated polyester film. However, our coating and coating procedure of the present invention may be applied to other types of polyester films. These films may have surfaces which have been irradiated, pretreated with various chemicals or otherwise subjected to certain treatments prior to the application of our antihalation and antistatic layer thereover.

In the above examples we have described the incorporation of our carbon component in a vehicle principally comprised of an acrylate-acrylic acid polymer. However, certain other vehicles may be employed. One particular vehicle which we favor inasmuch as it is useful on a wide variety of film bases comprises a combination of two components. That is, a combination of ethyl cellulose phthalate ground with 30% by weight of carbon black and methyl methacrylate-methacrylic acid copolymer ground with 30% carbon black (ratio of the two components 1 1), provides a good antihalation coating. There would be incorporated with the aforementioned composition at least 15% water and a small content of ammonium hydroxide.

While various types of carbon may be used, it has been observed that there is an inverse relation between the carbon particle size and conductivity as respects such particles for antistatic backings. A carbon of a particle size not exceeding about 18 m when applied to polyester sheets of the above type comprising latex coated oriented crystallized sheeting in a 1:1 carbon'vehicle ratio has a resistivity of the order of .01 10 ohms at an optical density of 0.2 at 550 m Carbon particles at a size of 43 m have substantially infinite resistivities at a density of 0.20. Accordingly, we prefer to employ a carbon having a particle size of not more than 30 III/.4.

In certain of the above examples, we have described the use of a spreading agent exemplified by Triton X-lOO which is a commercially available chemical comprised of p-tert-octylphenoxypolyethoxyethanol, as referred to above. We may use various other spreading agents such as Triton 770 which is sodium ,8-[6-(p-tert-octylphenoxy)- ethoxy]ethane sulfonate. Other agents which may be used as OMT which is oleoyl methyl taurine and product BCO which is cetyl betaine. In general we prefer to apply our antihalation and antistatic layers from an aqueous solution comprised at least of water and in many instances as high as 98% water. However, in the broader aspects of our invention the content of water while substantial may be as low as 15 or 20%.

Although in the above examples we have described applying the coatings by rollers as this is a particularly convenient and economical method, the aqueous coatings of the present invention may be applied by other types of apparatus such as extrusion or skim hoppers with air knife doctors. Our antistatic and anti-halation layers may be of any desired thickness or thinness. They may be of a thickness comparable to conventional coatings heretofore used. However, we prefer in general that our coatings while thin be of sufficient body to provide a continuous layer over the film base.

The invention has been described in detail with particular reference to preferred embodiments thereof, but it will be understood that variations and modifications v we is.

can be eflected within the spirit and scope of the invention as described hereinabove and as defined in the appended claims.

We claim:

1. The process of applying an antihalation layer to surfacesof polyester sheeting which sheeting in its manufacture has been coated with a latex, oriented and crystallized, which comprises preparing a coating solution consisting of at least 90% of water and containing acrylateacrylic acid polymer having saturated lower alkyl groups, ammonium hydroxide, a coloring ingredient and a spreading agent, applying this aqueous coating solution to the surface of said polyester film which carries a latex coating upon which the antihalation layer is desired, and drying the coating sufficiently to volatilize oif substantially all of the water and the ammonium constituent.

2. A process in accordance with claim 1 wherein the coloring agent is finely divided carbon.

3. A process in accordance with claim 1 wherein the coloring ingredient is carbon of a particle size not greater than 30 mg.

4. A process in accordance with claim 1 wherein the 1 coloring ingredient includes at least one dye from the group consisting of a yellow dye, a magenta dye and a green dye.

5. Aprocess in accordance with claim 1 wherein the polymer is essentially comprised of butyl methacrylate and methacrylic acid.

6. A process in accordance with claim 1 wherein the latex coating contains at least two of the constituents from the group consisting of acrylonitrile, vinylidene chloride, acrylic acid, itaconic acid and butyl acrylate.

7. The method of applying an antihalation coating onto photographic film base carrying a latex coating which comprises applying to the surface of the base upon which the antihalation coating is desired and upon said latex surface a solution containing at least 15% of water, a content of ammonia and the combination of ethyl cellulose phthalate containing ground-in carbon with methyl methacrylate methacrylic acid containing ground-in carbon and drying the coating thus applied sufliciently to volatilize oil substantially all of the water and ammonia components.

8. A method in accordance with claim 7 wherein the ratio of the ethyl cellulose phthalate carbon to the methyl methacrylate methacrylic acid carbon is about 1 l.

9. As an article of manufacture, a product comprised of a polyester sheet, said sheet having a latex coating thereon said latex coating carrying a layer of a material consisting of an acrylate-acrylic acid polymer having saturated lower alkyl groups, said polymer containing carbon particles of a size less than mn, said coating being characterized in that it is substantially water insoluble but soluble in photographic developer.

10. As an article of manufacture a product comprised of a polyester sheet, said sheet having a latex coating thereon which latex is comprised of at least two constituents from the group consisting of acrylonitrile, vinylidene chloride, acrylic acid, itaconic acid and butyl acrylate, said latex coating having applied thereto a layer consisting of an acrylate-acrylic acid polymer containing at least one dye from the group consisting of yellow dye, magenta dye and green dye said coating being characterized in that it is substantially water insoluble but soluble in photographic developer.

11. A product in accordance with claim 9 where in addition to the acrylate-acrylic acid polymer there is an ethyl cellulose phthalate component.

References Cited in the file of this patent UNITED STATES PATENTS 2,755,186 Saner July 17, 1956 2,772,166 Fowler Nov. 27, 1956 2,779,684 Alles Jan. 29, 1957 2,835,609 Starck May 20, 1958 2,852,378 Nadeau et al. Sept. 16, 1958 2,879,178 McWherter et a1. Mar. 24, 1959 

1. THE PROCESS OF APPLYING AN ANTIHALATION LAYER TO SURFACE OF POLYESTER SHEETING WHICH SHEETING IN ITS MANUFACTURE HAS BEEN COATED WITH A LATEX, ORIENTED AND CRYSTALLIZED, WHICH COMPRISES PREPARING A COATING SOLUTION CONSISTING OF AT LEAST 90% OF WATER AND CONTAINING ACRYLATEACRYLIC ACID POLYMER HAVING SATURATED LOWER ALKYL GROUPS, AMMONIUM HYDROXIDE, A COLORING INGREDIENT AND A SPREADING AGENT, APPLYING THIS AQUEOUS COATING SOLUTION TO THE SURFACE OF SAID POLYESTER FILM WHICH CARRIES A LATEX COATING UPON WHICH THE ANTIHALATION LAYER IS DESIRED, AND DRYING THE COATING SUFFICIENTLY TO VOLATIZE OFF SUBSTANTIALLY ALL OF THE WATER AND THE AMMONIUM CONSTITUENT.
 9. AS AN ARTICLE OF MANUFACTURE, A PRODUCT COMPRISED OF A POLYESTER SHEET, SAID SHEET HAVING LATEX COATING THEREON SAID LATEX COATING CARRYING A LAYER A LATEX COATING CONSISTING OF AN ACRYLATE-ACRYLIC ACID POLYMER HAVING SATURATED LOWER ALKYL GROUPS, SAID POLYMER CONTAINING CARBON PARTICLES OF A SIZE LESS THAN 30 MU, SAID COATING BEING CHARACTERIZED IN THAT IT IS SUBSTANTIALLY WATER INSOLUBLE BUT SOLUBLE IN PHOTOGRAPHIC DEVELOPER. 